Prognostic nutritional index predicts primary resistance to treatment and prognosis in metastatic castration-resistant prostate cancer atients reated with Abiraterone
Debate exists in regarding whether the observed PSA decline is a true surrogate for overall survival(OS) in patients with mCRPC. In addition, PSA flare phenomenon during Abiraterone (AA) treatment, which consists of an early and transient rise in the PSA level followed by a decline, had been reported by sevaral previous studies. So only PSA monitoring seems to be not reliable for evaluating the response to AA treatment of mCRPC patients. prognostic nutritional index (PNI), which is calculated on the basis of serum albumin levels and peripheral lymphocyte counts, may represent the nutritional and immunological status which could affect the survival rate of patients. Owing to this, higher baseline PNI level and PNI level elevation during AA treatment might indicate response to treatment and good clinical outcome of mCRPC. So we determined if PNI and its variation could predict initial resistance to treatment and prognosis in metastatic castration-resistant prostate cancer (mCRPC) patients treated with AA.
112 chemotherapy pretreated or chemotherapy-naive patients were scheduled for systemic treatment with AA. PNI levels were measured before and after one month of AA treatment. Univariate and multivariate logistic regression analyses were used to identify predictive factors of initial response to AA treatment. Univariable and multivariable Cox regression analyses were performed to determine prognostic factors that were associated with PSA progression-free survival (PSA-PFS), radiographic PFS (rPFS) and OS. The Harrell concordance index with variables only or combined PNI data were used to evaluate the prognostic accuracy.
81(72.3%) of 112 patients showed initial response to AA treatment, in which 15 experienced PSA flare during AA treatment. In multivariate logistic regression analyses, high baseline PNI level, PSA level decrease during the first month of AA treatment and PNI level elevation during the first month of AA treatment were significantly correlated with initial response to AA treatment. In multivariate Cox regression analysis, low PNI level remained significant predictors of OS, rPFS and PSA-PFS. The estimated c-index of the multivariate model for OS increased from 0.82 without PNI to 0.83 when PNI added.
Independent of PSA level variation, PNI level elevation during the first month of AA treatment and high baseline PNI level were significantly correlated with initial response to AA treatment. In addition, low pretreatment PNI level is a negative independent prognosticator of survival outcomes in mCRPC treated with AA and also increases the accuracy of established prognostic model.